Inbred corn lines LH185

ABSTRACT

An inbred corn line, designated LH185, is disclosed. The invention relates to the seeds of inbred corn line LH185, to the plants of inbred corn line LH185 and to methods for producing a corn plant produced by crossing the inbred line LH185 with itself or another corn line. The invention further relates to hybrid corn seeds and plants produced by crossing the inbred line LH185 with another corn line.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinctive corn inbred line,designated LH185. There are numerous steps in the development of anynovel, desirable plant germplasm. Plant breeding begins with theanalysis and definition of problems and weaknesses of the currentgermplasm, the establishment of program goals, and the definition ofspecific breeding objectives. The next step is selection of germplasmthat possess the traits to meet the program goals. The goal is tocombine in a single variety or hybrid an improved combination ofdesirable traits from the parental germplasm. These important traits mayinclude higher yield, resistance to diseases and insects, better stalksand roots, tolerance to drought and heat, and better agronomic quality.

Choice of breeding or selection methods depends on the mode of plantreproduction, the heritability of the trait(s) being improved, and thetype of cultivar used commercially (e.g., F₁, hybrid cultivar, purelinecultivar, etc.). For highly heritable traits, a choice of superiorindividual plants evaluated at a single location will be effective,whereas for traits with low heritability, selection should be based onmean values obtained from replicated evaluations of families of relatedplants. Popular selection methods commonly include pedigree selection,modified pedigree selection, mass selection, and recurrent selection.

The complexity of inheritance influences choice of the breeding method.Backcross breeding is used to transfer one or a few favorable genes fora highly heritable trait into a desirable cultivar. This approach hasbeen used extensively for breeding disease-resistant cultivars. Variousrecurrent selection techniques are used to improve quantitativelyinherited traits controlled by numerous genes. The use of recurrentselection in self-pollinating crops depends on the ease of pollination,the frequency of successful hybrids from each pollination, and thenumber of hybrid offspring from each successful cross.

Each breeding program should include a periodic, objective evaluation ofthe efficiency of the breeding procedure. Evaluation criteria varydepending on the goal and objectives, but should include gain fromselection per year based on comparisons to an appropriate standard,overall value of the advanced breeding lines, and number of successfulcultivars produced per unit of input (e.g., per year, per dollarexpended, etc.).

Promising advanced breeding lines are thoroughly tested and compared toappropriate standards in environments representative of the commercialtarget area(s) for three years at least. The best lines are candidatesfor new commercial cultivars; those still deficient in a few traits areused as parents to produce new populations for further selection.

These processes, which lead to the final step of marketing anddistribution, usually take from eight to 12 years from the time thefirst cross is made. Therefore, development of new cultivars is atime-consuming process that requires precise forward planning, efficientuse of resources, and a minimum of changes in direction.

A most difficult task is the identification of individuals that aregenetically superior, because for most traits the true genotypic valueis masked by other confounding plant traits or environmental factors.One method of identifying a superior plant is to observe its performancerelative to other experimental plants and to a widely grown standardcultivar. If a single observation is inconclusive, replicatedobservations provide a better estimate of its genetic worth.

The goal of plant breeding is to develop new, unique and superior corninbred lines and hybrids. The breeder initially selects and crosses twoor more parental lines, followed by repeated selfing and selection,producing many new genetic combinations. The breeder can theoreticallygenerate billions of different genetic combinations via crossing,selfing and mutations. The breeder has no direct control at the cellularlevel. Therefore, two breeders will never develop the same line, or evenvery similar lines, having the same corn traits. Each year, the plantbreeder selects the germplasm to advance to the next generation. Thisgermplasm is grown under unique and different geographical, climatic andsoil conditions, and further selections are then made, during and at theend of the growing season. The inbred lines which are developed areunpredictable. This unpredictability is because the breeder's selectionoccurs in unique environments, with no control at the DNA level (usingconventional breeding procedures), and with millions of differentpossible genetic combinations being generated. A breeder of ordinaryskill in the art cannot predict the final resulting lines he develops,except possibly in a very gross and general fashion. The same breedercannot produce the same line twice by using the exact same originalparents and the same selection techniques. This unpredictability resultsin the expenditure of large research monies to develop a superior newcorn inbred line.

The development of commercial corn hybrids requires the development ofhomozygous inbred lines, the crossing of these lines, and the evaluationof the crosses. Pedigree breeding and recurrent selection breedingmethods are used to develop inbred lines from breeding populations.Breeding programs combine desirable traits from two or more inbred linesor various broad-based sources into breeding pools from which inbredlines are developed by selfing and selection of desired phenotypes. Thenew inbreds are crossed with other inbred lines and the hybrids fromthese crosses are evaluated to determine which have commercialpotential.

Pedigree breeding is used commonly for the improvement ofself-pollinating crops or inbred lines of cross-pollinating crops. Twoparents which possess favorable, complementary traits are crossed toproduce an F₁. An F2 population is produced by selfing one or several F₁'s or by intercrossing two F₁ 's (sib mating). Selection of the bestindividuals is usually begun in the F₂ population; then, beginning inthe F₃, the best individuals in the best families are selected.Replicated testing of families, or hybrid combinations involvingindividuals of these families, often follows in the F₄ generation toimprove the effectiveness of selection for traits with low heritability.At an advanced stage of inbreeding (i.e., F₆ and F₇), the best lines ormixtures of phenotypically similar lines are tested for potentialrelease as new cultivars.

Mass and recurrent selections can be used to improve populations ofeither self- or cross-pollinating crops. A genetically variablepopulation of heterozygous individuals is either identified or createdby intercrossing several different parents. The best plants are selectedbased on individual superiority, outstanding progeny, or excellentcombining ability. The selected plants are intercrossed to produce a newpopulation in which further cycles of selection are continued.

Backcross breeding has been used to transfer genes for a simplyinherited, highly heritable trait into a desirable homozygous cultivaror inbred line which is the recurrent parent. The source of the trait tobe transferred is called the donor parent. The resulting plant isexpected to have the attributes of the recurrent parent (e.g., cultivar)and the desirable trait transferred from the donor parent. After theinitial cross, individuals possessing the phenotype of the donor parentare selected and repeatedly crossed (backcrossed) to the recurrentparent. The resulting plant is expected to have the attributes of therecurrent parent (e.g., cultivar) and the desirable trait transferredfrom the donor parent.

Descriptions of other breeding methods that are commonly used fordifferent traits and crops can be found in one of several referencebooks (e.g., Allard, 1960; Simmonds, 1979; Sneep et al., 1979; Fehr,1987).

Proper testing should detect any major faults and establish the level ofsuperiority or improvement over current cultivars. In addition toshowing superior performance, there must be a demand for a new cultivarthat is compatible with industry standards or which creates a newmarket. The introduction of a new cultivar will incur additional coststo the seed producer, the grower, processor and consumer; for specialadvertising and marketing, altered seed and commercial productionpractices, and new product utilization. The testing preceding release ofa new cultivar should take into consideration research and developmentcosts as well as technical superiority of the final cultivar. Forseed-propagated cultivars, it must be feasible to produce seed easilyand economically.

Once the inbreds that give the best hybrid performance have beenidentified, the hybrid seed can be reproduced indefinitely as long asthe homogeneity of the inbred parent is maintained. A single-crosshybrid is produced when two inbred lines are crossed to produce the Fprogeny. A double-cross hybrid is produced from four inbred linescrossed in pairs (AxB and CxD) and then the two F₁ hybrids are crossedagain (AxB) x (CxD). Much of the hybrid vigor exhibited by F₁ hybrids islost in the next generation (F₂). Consequently, seed from hybridvarieties is not used for planting stock.

Corn is an important and valuable field crop. Thus, a continuing goal ofplant breeders is to develop stable, high yielding corn hybrids that areagronomically sound. The reasons for this goal are obviously to maximizethe amount of grain produced on the land used and to supply food forboth animals and humans. To accomplish this goal, the corn breeder mustselect and develop corn plants that have the traits that result insuperior parental lines for producing hybrids.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred corn line,designated LH185. This invention thus relates to the seeds of inbredcorn line LH185, to the plants of inbred corn line LH185 and to methodsfor producing a corn plant produced by crossing the inbred line LH185with itself or another corn line. This invention further relates tohybrid corn seeds and plants produced by crossing the inbred line LH185with another corn line.

DEFINITIONS

In the description and tables which follow, a number of terms are used.In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided:

Predicted RM. This trait for a hybrid, predicted relative maturity (RM),is based on the harvest moisture of the grain. The relative maturityrating is based on a known set of checks and utilizes conventionalmaturity systems such as the Minnesota Relative Maturity Rating System.

MN RM. This represents the Minnesota Relative Maturity Rating (MN RM)for the hybrid and is based on the harvest moisture of the grainrelative to a standard set of checks of previously determined MN RMrating. Regression analysis is used to compute this rating.

Yield (Bushels/Acre). The yield in bushels/acre is the actual yield ofthe grain at harvest adjusted to 15.5% moisture.

Moisture. The moisture is the actual percentage moisture of the grain atharvest.

GDU Silk. The GDU silk (=heat unit silk) is the number of growing degreeunits (GDU) or heat units required for an inbred line or hybrid to reachsilk emergence from the time of planting. Growing degree units arecalculated by the Barger Method, where the heat units for a 24-hourperiod are: ##EQU1## The highest maximum used is 86° F. and the lowestminimum used is 50° F. For each hybrid, it takes a certain number ofGDUs to reach various stages of plant development. GDUs are a way ofmeasuring plant maturity.

Stalk Lodging. This is the percentage of plants that stalk lodge, i.e.,stalk breakage, as measured by either natural lodging or pushing thestalks determining the percentage of plants that break off below theear. This is a relative rating of a hybrid to other hybrids forstandability.

Root Lodging. The root lodging is the percentage of plants that rootlodge; i.e., those that lean from the vertical axis at an approximate30° angle or greater would be counted as root lodged.

Plant Height. This is a measure of the height of the hybrid from theground to the tip of the tassel, and is measured in centimeters.

Ear Height. The ear height is a measure from the ground to the ear nodeattachment, and is measured in centimeters.

Dropped Ears. This is a measure of the number of dropped ears per plot,and represents the percentage of plants that dropped an ear prior toharvest.

DETAILED DESCRIPTION OF THE INVENTION

Inbred corn line LH185 is a yellow dent corn with superiorcharacteristics, and provides an excellent parental line in crosses forproducing first generation (F₁ hybrid corn.

LH185 was developed from the single cross LH59 ×LH123Ht by selfing andusing the pedigree system of plant breeding. Selfing and selection werepracticed within the above F₁ cross for seven generations in thedevelopment of LH185.

Some of the criteria used to select ears in various generations include:yield, stalk quality, root quality, disease tolerance, late plantgreenness, late season plant intactness, ear retention, pollen sheddingability, silking ability, and corn borer tolerance. During thedevelopment of the line, crosses were made to inbred testers for thepurpose of estimating the line's general and specific combining ability,and evaluations were run by the Williamsburg, Iowa Research Station. Theinbred was evaluated further as a line and in numerous crosses by theWilliamsburg and other research stations across the Corn Belt. Theinbred has proven to have a very good combining ability in hybridcombinations.

The inbred has shown uniformity and stability for all traits, asdescribed in the following variety description information. It has beenself-pollinated and ear-rowed a sufficient number of generations, withcareful attention to uniformity of plant type to ensure homozygosity andphenotypic stability. The line has been increased both by hand andsibbed in isolated fields with continued observation for uniformity. Novariant traits have been observed or are expected in LH185.

Inbred corn line LH185 has the following morphologic and othercharacteristics (based primarily on data collected at Williamsburg,Iowa):

VARIETY DESCRIPTION INFORMATION

A. Maturity

INBRED=LH185

Best Adapted For: Northcentral Regions of the Corn Belt

Heat Unit Silk: 1455 ##EQU2##

B. Plant Characteristics

Plant height (to tassel tip): 163 cm.

Length of top ear internode: 13 cm.

Number of tillers: None

Cytoplasm type: Normal

Number of ears per stalk: Single

Ear height (to base of top ear): 35 cm.

C. Leaf

Color: 7.5 GY 3/4 Munsell Color Charts for Plant Tissues

Angle from stalk: 30°-60°

Marginal waves: Few

Width (widest point of ear node leaf): 8 cm.

Number of leaves (mature plants): 12

Sheath pubescence: Light

Longitudinal creases: Few

Length (ear node leaf): 59 cm.

D. Tassel

Number of lateral branches: 4

Branch angle from central spike: 30°-40°

Pollen shed: Medium

Anther color: Yellow

Glume color: Green

Peduncle length (top leaf to basal branch): 03 cm.

E. Ear (Husked Ear Data Except When Stated Otherwise)

Length: 12 cm.

Midpoint diameter: 35 ram.

Weight: 38 gm.

Number of Kernel rows: 10

Silk color: Green

Husk color (fresh): Light green

Husk color (dry): Buff

Husk extension: Long (8-10 cm.)

Shank length: 05 cm.

Shank (no. of internodes): 8

Taper of Ear: Slight

Husk leaf: Medium--8-15 cm.

Position of shank (dry husks): Upright

F. Kernel (Dried)

Size (from ear midpoint)

Length: 11 mm.

Width: 10 mm.

Thickness: 4 mm.

Shape grade (% rounds): 40-60

Pericarp color: Bronze

Aleurone color: White

Endosperm color: Yellow

Endosperm type: Normal starch

Gm Weight/100 seeds (unsized): 27 gm.

G. Cob

Diameter at midpoint: 25 mm.

Strength: Strong

Color: White

LH185 is a line developed from the parents LH59 and LH123. LH185 as aplant resembles more closely the LH123 parent except LH185 is a shorterplant with a very low ear placement. LH185 is earlier flowering thanLH123. In hybrid combination, the ear type is somewhat like LH123(relatively short and girthy).

LH185 has a much greater area of adaptability than LH123 had when LH123was used commercially. One particular agronomic trait that increasesLH185's area of adaptation over LH 123 is LH 185's improved resistanceto summer stalk brittling. This was a particularly limiting problem thatwas characteristic of LH123 in a number of hybrids.

LH185 has very good general combining ability. LH185's yield to moistureratio is improved over either parent.

TABLES

In the tables that follow, the traits and characteristics of inbred cornline LH185 are given in hybrid combination. The data collected on inbredcorn line LH185 is presented for the key characteristics and traits. Thetables present yield test information about LH185. LH185 was tested inseveral hybrid combinations at numerous locations, with two or threereplications per location. Information about these hybrids, as comparedto several check hybrids, is presented.

The first pedigree listed in the comparison group is the hybridcontaining LH185. Information for the pedigree includes:

1. Mean yield of the hybrid across all locations.

2. A mean for the percentage moisture (% M) for the hybrid across alllocations.

3. A mean of the yield divided by the percentage moisture (Y/M) for thehybrid across all locations.

4. A mean of the percentage of plants with stalk lodging (% SL) acrossall locations.

5. A mean of the percentage of plants with root lodging (% RL) acrossall locations.

6. A mean of the percentage of plants with dropped ears (% DE).

7. The number of locations indicates the locations where these hybridswere tested together.

The series of hybrids listed under the hybrid containing LH185 areconsidered check hybrids. The check hybrids are compared to hybridscontaining the inbred LH 185.

The (+) or (-) sign in front of each number in each of the columnsindicates how the mean values across plots of the hybrid containinginbred LH185 compare to the check crosses. A (+) or (-) sign in front ofthe number indicates that the mean of the hybrid containing inbred LH185was greater or lesser, respectively, than the mean of the check hybrid.For example, a +4 in yield signifies that the hybrid containing inbredLH185 produced 4 bushels more corn than the check hybrid. If the valueof the stalks has a (-) in front of the number 2, for example, then thehybrid containing the inbred LH185 had 2% less stalk lodging than thecheck hybrid.

                  TABLE 1                                                         ______________________________________                                        Overall Comparisons of                                                        LH185 × LH195 Hybrid Vs. Check Hybrid                                              Mean                             %                                 Hybrid     Yield    % M    Y/M  % SL  % RL  DE                                ______________________________________                                        LH185 × LH195                                                                      227      20.95  10.82                                                                              1     6     0                                 (at 16 Loc's)                                                                 as compared to:                                                               LH195 × LH212                                                                      +7       -.67   +.64 -3    +1    0                                 LH132 × LH212                                                                      +16      -.43   +.53 -3    +1    0                                 LH195 × LH59                                                                       +14      +.64   +.36 -1    +3    0                                 LH195 × LH184                                                                      +14      +.67   +.34 -1    +3    0                                 ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Overall Comparisons of                                                        LH185 × LH198 Hybrid Vs. Check Hybrid                                              Mean                             %                                 Hybrid     Yield    % M    Y/M  % SL  % RL  DE                                ______________________________________                                        LH185 × LH198                                                                      221      20.54  10.78                                                                              1     7     0                                 (at 21 Loc's)                                                                 as compared to:                                                               LH132 × LH82                                                                       +29      -1.34  +2.02                                                                              -1    +1    0                                 LH204 × LH212                                                                      +7       -.63   +.65 -2    +2    0                                 LH132 × LH59                                                                       +15      -.37   +.92 -1    +2    0                                 LH205 × LH216                                                                      +21      -.34   +1.17                                                                              0     +1    0                                 LH198 × LH59                                                                       +12      -.04   +.59 0     +1    0                                 LH198 × LH82                                                                       +27      +.09   +1.29                                                                              -1    -4    0                                 ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Overall Comparisons of                                                        LH185 × LH132 Hybrid Vs. Check Hybrid                                              Mean                             %                                 Hybrid     Yield    % M    Y/M  % SL  % RL  DE                                ______________________________________                                        LH185 × LH132                                                                      211      21.42  9.85 1     6     0                                 (at 17 Loc's)                                                                 as compared to                                                                LH132 × LH212                                                                      +3       -.86   +.51 -1    +3    0                                 LHE136 × LH82                                                                      +22      -.03   +1.05                                                                              -1    +3    0                                 LH132 × LH59                                                                       +17      +.44   +.61 -1    +1    0                                 LH204 × LH212                                                                      +2       +.91   -.37 -2    +1    0                                 ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Overall Comparisons of                                                        LH185 × LH74 Hybrid Vs. Check Hybrid                                               Mean                             %                                 Hybrid     Yield    % M    Y/M  % SL  % RL  DE                                ______________________________________                                        LH185 × LH74                                                                       189      20.91  9.03 3     4     0                                 (at 21 Loc's)                                                                 as compared to                                                                LH74 × LH51                                                                        +1       -2.31  +.95 -1    -1    0                                 LH216 × LH206                                                                      +1       -1.84  +.76 +2    0     0                                 LH132 × LH165                                                                      +11      -1.09  +.96 0     -1    0                                 LH132 × LH167                                                                      +1       -.34   +.18 -1    -1    0                                 LH202 × LH82                                                                       +14      -.08   +.64 -4    -2    0                                 ______________________________________                                    

DEPOSIT INFORMATION

Inbred seeds of LH185 have been placed on deposit with the American TypeCulture Collection (ATCC), Rockville, Md. 20852, under Deposit AccessionNumber 75618 on Dec. 3, 1993. A Plant Variety Protection Certificate isbeing applied for with the United States Department of Agriculture.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

What is claimed is:
 1. Inbred corn seed designated LHI85 having ATCCaccession No.
 75618. 2. A corn plant produced by growing the seed ofclaim
 1. 3. Pollen of the plant of claim
 2. 4. An ovule of the plant ofclaim
 2. 5. An inbred corn plant having all the physiological andmorphological characteristics of the corn plant of claim
 2. 6. A tissueculture comprising regenerable cells of the inbred corn plant designatedLH185.
 7. A corn plant regenerated from said tissue culture of claim 6,wherein said regenerated corn plant has all the physiological andmorphological characteristics of the corn plant of LH185.